This L-shaped brush is the perfect tool for scrubbing every inch on the inside of carboys, and thanks to the plastic coating, they're also safe to use with plastic fermenters and PET carboys. Normal carboy brushes like our CE40 are great for cleaning glass carboys, but can be a risky choice for using on plastic. The metal rod where the bristles attach can scratch plastic, creating hide outs for bacteria. You won't have those worries with this carboy brush!